Plane lattice hollow concrete slab and cross arm brace

ABSTRACT

In order to obtain a plane lattice hollow concrete slab having a high workability and a high sound insulating property, and a cross arm brace used in the plane lattice hollow concrete slab, the plane lattice hollow concrete slab comprises a light weight body  5  buried in a small space  4  which is partitioned on a grid by upper reinforcing bars  3   a  and  3   b  and lower reinforcing bars  2   a  and  2   b  positioned on a grid in a slab. The light weight body is a solid-core or a hollow light weight ball body. The light weight body has a diameter which passes through a top surface of the small space and which does not pass through a side surface of the small space. The light weight body is fixed to a predetermined position by a cross arm brace which is positioned on the upper reinforcing bar. The cross arm brace comprises at least two auxiliary reinforcing bars positioned in parallel between upper reinforcing bars adjacent to each other, and a plurality of units each of which is fixed downwardly on the auxiliary reinforcing bar. Each of the units is inserted into a small space formed by upper reinforcing bars which are positioned on a grid. A light weight ball body is fixed to a predetermined position of the small space.

BACKGROUND OF THE INVENTION

The present invention relates to a plane lattice hollow concrete slabhaving a high workability and a high sound insulating property, and across arm brace used in the concrete slab.

In order to make a building be high-rise or to secure a wide room space,a construction method is realized which increases a strength byincreasing a thickness of ferroconcrete slab. In order to accomplish aweight saving and to improve a sound insulating property, anotherconstruction method is realized which makes the concrete slab be hollowby burying a buried object in the concrete slab. A hollow pipe, a boxshaped artifact, or a water resistant corrugated cardboard is used assuch a buried object. The hollow pipe may be, for example, a windingpipe. The box shaped artifact may be made of a bent steel deck or bentkeystone plate. In addition, proposal is made in Japanese PatentPublication Tokko Syo 57-47007 or Japanese Patent Publication Tokko Syo58-20768 about a construction method using a synthetic resin foam as theburied object and using a mold form which is fixedly integrated to athin PC base plate.

Although it is possible to accomplish the weight saving in each of theabove-mentioned conventional construction methods, the concrete slab isa unidirectional slab in which a hollow portion continues in a singledirection, in each of the conventional construction methods. Inasmuch asthe unidirectional concrete slab structurally transmits a load in thesingle direction, there are architectonic constraints in case of theslab which carries out a support on four sides. In order to dissolve theabove-mentioned problem, proposal is made in Japanese Patent PublicationTokko Syo 63-49025 about a bi-directional slab. However, it is necessaryfor the bi-directional slab using the hollow pipe to take a lot oftrouble with design, on carrying out arrangement of the hollow pipe ateach of slabs or articles. Furthermore, material management becomescomplicate inasmuch as it is necessary to provide various sizes ofhollow pipes. In addition, it is necessary to take a lot of trouble withconstruction.

In order to drastically improve the conventional hollow slabconstruction method, proposal is made in Japanese Unexamined PatentPublication Tokkai Hei 9-250196 about a construction method in whichconcrete runs in the mold form after a plurality of light weight bodiesare located in small spaces compartmentalized on grids by topreinforcements and bottom reinforcements which are positioned at alattice shape in the mold form. In the bi-directional slab constructionmethod, the light weight body such as plastic foam, which has a dieshape, a column shape, or a Japanese lantern shape, is used and isburied in each of the small spaces which are regularly formed at thelattice shape of the slab, in order to form the bi-directional slabhaving a cross section that beams of I type are met to each other in twodirections perpendicular to each other. By the above-mentionedstructure, it is easy to carry out the material management. On theexecution of construction, the light weight body is only supported inthe above-mentioned small space by an auxiliary reinforcing bar. As aresult, it is possible to briefly form the bi-directional slab havinghigh accuracy.

However, the bi-directional slab described in the above-mentionedPublication has following problems.

On forming a slab bone structure A shown in FIG. 13, an auxiliaryreinforcing bar 24 a is positioned in a middle of a lower reinforcingbar 22 a and an auxiliary reinforcing bar 24 b is positioned in a middleof a lower reinforcing bar 22 b, on a lower mold form 21. After upperreinforcing bars 23 a and 23 b are positioned and a light weight body 25is positioned, it is necessary to position an auxiliary reinforcing bar24 c between the upper reinforcing bar 23 a and the upper reinforcingbar 23 b. In order to prevent the light weight body 25 from lifting oncasting concrete, it is necessary to fix the bottom portion of the lightweight body 25 by the auxiliary reinforcing bars 24 a and 24 b and tofix the top portion of the light weight body 25 by the auxiliaryreinforcing bar 24 c. The auxiliary reinforcing bars hardly contributeto strength improvement of the slab. In addition, orientations occurtowards up and down and right and left in the light weight body inasmuchas the light weight body has grooves each of which receives theauxiliary reinforcing bar. As a result, it is necessary to accuratelyposition the light weight body with meeting the orientations, on theexecution of construction. Accordingly, expenses are piling up and it isnecessary to take a lot of trouble with setting of the light weightbody. Cost increases on the execution of construction.

SUMMARY OF THE INVENTION

In order to dissolve the problems of the conventional bi-directionalslab, it is an object of the present invention to provide a planelattice hollow concrete slab having a high workability and a high soundinsulating property, and a cross arm brace used in the concrete slab.

According to the present invention, there is provided a plane latticehollow concrete slab comprising a light weight body buried in a smallspace which is partitioned on a grid by an upper reinforcing bar and alower reinforcing bar positioned on a grid in a slab. The light weightbody is a solid-core or a hollow light weight ball body. The lightweight body has a diameter which passes through a top surface of thesmall space and which does not pass through a side surface of the smallspace. The light weight body is fixed to a predetermined position by across arm brace which is positioned on the upper reinforcing bar.

In the plane lattice hollow concrete slab of the present invention, avolume ratio of said small space to said light weight ball body may beselected from 10% to 50%.

According to the present invention, there is provided a cross arm bracefor a plane lattice hollow concrete slab. The cross brace comprises atleast two auxiliary reinforcing bars positioned in parallel betweenupper reinforcing bars adjacent to each other, and a plurality of unitseach of which is fixed downwardly on the auxiliary reinforcing bar. Eachof the units is inserted into a small space formed by upper reinforcingbars which are positioned on a grid. A light weight ball body is fixedto a predetermined position of the small space.

In the cross arm brace of the present invention, each of the units is anendless frame reinforcing bar which is bent to a saddle shape.Preferably, each of the units has a leg portion which is bent to anouter side. In addition, each of the units comprises holding reinforcingbars which are bent so as to form a valley. The holding reinforcing barsare positioned one after the other with inclination. Both ends are notconnected to each other in each of the holding reinforcing bars.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plane view for illustrating a slab bone structure ofconcrete slab according to an embodiment of the present invention;

FIG. 2 shows a vertical sectional view along A-A′ line of FIG. 1;

FIG. 3 shows a vertical sectional view along B-B′ line of FIG. 1;

FIG. 4 shows a prospective view in a condition of cutting off theconcrete of FIG. 1;

FIG. 5 shows a prospective view for illustrating a cross arm braceaccording to an embodiment of the present invention;

FIG. 6 shows a plane view of the cross arm brace;

FIG. 7 shows a front view of the cross arm brace;

FIG. 8 shows a plane view of a unit for forming the cross arm brace;

FIG. 9 shows a vertical sectional view along A-A′ line of FIG. 8;

FIG. 10 shows a vertical sectional view along B-B′ line of FIG. 8;

FIG. 11 shows a prospective view for illustrating a cross arm braceaccording to another embodiment of the present invention;

FIG. 12 shows a prospective view for illustrating a cross arm braceaccording to further another embodiment of the present invention; and

FIG. 13 shows a view for illustrating a bone structure of a conventionalplane lattice hollow concrete slab.

PREFERRED EMBODIMENT OF THE INVENTION

Description will be made as regards a plane lattice hollow concrete slab(which will be merely called a concrete slab hereinafter) according toan embodiment of the present invention. The present invention is notlimited to the feature which will be described hereinafter. It ispossible to replace each element and to carry out change of designwithin a range in which the object of the present invention isaccomplished.

FIG. 1 shows a plane view for illustrating a slab bone structure of theconcrete slab. FIG. 2 shows a vertical sectional view along A-A′ line ofFIG. 1. FIG. 3 shows a vertical sectional view along B-B′ line ofFIG. 1. FIG. 4 shows a prospective view in a condition of cutting offthe concrete of FIG. 1.

The slab bone structure shown in a reference symbol S comprises lowerreinforcing bars 2 a and 2 b and upper reinforcing bars 3 a and 3 b. Thelower reinforcing bar 2 b is positioned perpendicular to the lowerreinforcing bars 2 a which are positioned parallel to each other, on alower mold form 1 of the slab. Similarly, the upper reinforcing bars 3 aand 3 b are positioned perpendicular to the lower reinforcing bars 2 a.As a result, a plurality of small spaces 4, which are partitioned ongrids, are formed in a lattice shape. Light weight ball bodies 5 arepositioned in the small spaces 4, respectively. The cross arm brace 6 ispositioned on the upper reinforcing bar 3 b, in order to prevent each oflight weight ball bodies 5 from movement. The lower reinforcing bar 2 band the upper reinforcing bar 3 b is fixed by a width stop reinforcingbar 7.

A mold form, which is made of wood, plastic or the like, is used as thelower mold form 1. Instead of the mold form 1, a deck constructionmethod using a deck plate may be employed. Alternatively, a half PCconstruction method or a full PC construction method may be employedwhich uses a precast concrete.

It is desired that the interval of main reinforcing bar varies inaccordance with a designed thickness of the concrete slab. The intervalis indicative of an interval between one lower reinforcing bar 2 a andan adjacent lower reinforcing bar 2 a and between one lower reinforcingbar 2 a and an adjacent lower reinforcing bar 2 a, in case of lowerreinforcing bars. When the size of the light weight ball body 5 varieson the basis of the slab thickness, it is advantageous to improve thelight weight and the sound insulating property with maintaining the slabrigidity. In addition, the interval between the lower reinforcing bar 2a and the upper reinforcing bar 3 a may be determined on the basis ofthe slab thickness and the concrete cover thickness.

Although the width stop reinforcing bar 7 is not limited which iscapable of fixing the upper reinforcing bar and the lower reinforcingbar, it is desired that the width stop reinforcing bar 7 is made of areinforcing bar having about 10 mmφ-15 mmφ and cut to a predeterminedlength. One end of the width stop reinforcing bar 7 is bent to an acuteangle and another end of the width stop reinforcing bar 7 is bent toabout right angle. Alternatively, the width stop reinforcing bar 7 isused which a reinforcing bar cut to a predetermined length. The widthstop reinforcing bar 7 may be fixed to the upper reinforcing bar and thelower reinforcing bar by using a fixing means such as a welding,adhesive bonding, branch tying, or the like.

The light weight ball body 5 used in the concrete slab according to thepresent invention has a diameter which is capable of passing through atop surface of the small space 4 and which is not capable of passingthrough a side surface of the small space 5. In case where the diameter(φ) of the light weight ball body 5 is not greater than that of the sidesurface of the small space 4, the light weight ball body 5 may stick outfrom one small space 5 to another small space 5 or may move from onesmall space 5 to another small space 5. In addition, it is impossible toposition the light weight ball body 5 in the small space 4 in case wherethe diameter p can not pass through the top surface of the small space4. As described above, one light weight ball body 5 enters in one smallspace 4 by defining the size of the light weight ball body in relationto the small space 4.

When the light weight ball body 5 has the above-mentioned conditions, itis sufficient to provide six kinds of light weight ball bodies whosediameters is equal to S(φ125 mm), M(φ150 mm), L(φ175 mm), 2L(φ200 mm),3L(φ225 mm), and 4l(φ250 mm), respectively. These light weight ballbodies can meet the slab thickness from 225 mm to 350 mm. Using thelight weight ball body having an optional diameter, it is possible tomeet an optional slab thickness.

It is desired that the shape of the light weight ball body has aspherical shape as far as possible. Although it is possible for theshape of the light weight ball body to be somewhat of irregular shape,it is necessary to align the light weight ball body in direction on theexecution of construction, inasmuch as an ellipsoid shape or an ovoidshape such as a rugby ball has an orientation. When concavity andconvexity or a shallow groove is formed on the surface of the lightweight ball body, the light weight ball body makes friends with theconcrete. The material of the light weight ball body is not limited incase where the material is light and can be easily worked. For example,it is possible to use a hollow body such as plastic foam or a plastichollow body. More particularly, it is preferable to use a solid-corebody of plastic foam such as polystyrene foam or polyethylene foam whichhas rigidity.

According to the present invention, it is possible to correctly positionone light weight ball body 5 in one small space 4 when the light weightball body only drops in the small space 4, inasmuch as the light weightball body has no orientation. On the other hand, efficiency greatlyreduces on the execution of construction inasmuch as it is necessary toalign each of the light weight bodies in direction, when using theconventional light weight body having the orientation.

In the present invention, it is desired that a ratio (volume ratio) ofthe light weight ball body to the small space is about 10% to 50%. Incase where the volume ratio is less than 10%, it is difficult to makethe concrete slab be light and it is difficult to improve the soundinsulating property. In case where the volume ratio is greater than 50%,the rigidity of the concrete slab reduces. From a balance of therigidity and lightness of the concrete slab, it is desired for thevolume ratio to be from 15% to 35%. Furthermore, it is preferable forthe volume ratio to be from 18% to 32%. Although Table 1 shows desiredexamples of slab thickness, sectional gap (gap between the lowerreinforcing bar 2 a and upper reinforcing bar 3 a), void diameter, andvolume ratio, the present invention is not limited to Table 1. TABLE 1slab thickness mm 225 250 275 300 325 350 cross-sectional gap mm 115 140165 190 215 240 void diameter Φ mm 125 150 175 200 225 250 void volumecm³ 1023 1767 2806 4189 5964 8181 volume ratio % 20.2 23.1 25.5 27.629.4 30.9 the number of pieces 4444 3265 2500 1975 1600 1322 smallspaces

After the light weight ball bodies 5 are positioned in a plurality ofsmall spaces 4, respectively, the cross arm brace 6 is mounted on theupper reinforcing bar 3 b and is bonded to the upper reinforcing bar 3a. In case where the light weight ball body 5 is only positioned in thesmall space 5, the light weight body 5 floats from the small space 5 oncasting a freshly mixed concrete. As a result, the light weight ballbodies 5 may escape from the small spaces to gather on the surface ofthe slab. Each of the light weight ball bodies 5 may be shifted from apredetermined position. In order to dissolve the above-mentionedproblem, each of the light weight ball bodies 5 is fixed by the crossarm brace 6 according to the present invention. It is possible to usethe cross arm brace 6 as a scaffold for piping work, wiring work, or thelike. Furthermore, it is possible to prevent the light weight ball bodyfrom damage by using cross arm brace.

Next, description will proceed to an example of the cross arm brace forconcrete slab according to the present invention, with reference todrawings. FIG. 5, FIG. 6, and FIG. 7 show a prospective view, a planeview, and a front view each of which shows the cross arm brace accordingto an embodiment of the present invention. FIG. 9 shows a plane view forillustrating an unit for forming the cross arm brace. FIG. 9 shows avertical sectional view along A-A′ line of FIG. 8. FIG. 10 shows avertical sectional view along B-B′ line of FIG. 8.

The cross arm brace 11 comprises two auxiliary reinforcing bars 12 and12′ and a plurality of units 13, 13′, 13″, 13′″, 13″″, . . . The unit 13shown in FIG. 5 has endless box shape in FIG. 8. The unit 13 shown inFIG. 5 has a mount shape such as Mt. Fuji in FIG. 9. The unit 13 shownin FIG. 5 has a box shape having no top portion, in FIG. 10. The unit 13is fixed to the auxiliary reinforcing bars 12 and 12′ with straddling toa saddle shape. The unit 13 can be inserted into the small spaceillustrated in FIG. 1. The light weight ball body 14 is held in a spaceformed by the unit 13 which is for fixing the light weight ball body 14with no movement. Although it is sufficient to provide two auxiliaryreinforcing bars as shown in the drawings, at least three auxiliaryreinforcing bars may be provided. In case of using one auxiliaryreinforcing bar, the auxiliary reinforcing bar becomes a rotation axisand the cross arm brace rotates around the rotation axis. Therefore, itis necessary to fix the auxiliary reinforcing bar to the upperreinforcing bar by means of welding or the like. Although the auxiliaryreinforcing bar is optional in thickness and length, it is easy to carryout the design and the execution of construction inasmuch as it is easyto deal with the auxiliary reinforcing bar, when a reinforcing barhaving a diameter of 6 mmφ and a length of about 1.9 m may be used asthe auxiliary reinforcing bar.

A reinforcing bar is bent to a rectangular shape whose ends are weldedto each other, in order to make a rectangular frame bar. The rectangularframe bar is bent to a predetermined shape to be formed to the unit 13.The unit 13 is mounted on two auxiliary reinforcing bars 12 and 12′ soas to direct the bent side of the unit 13 to a lower direction. Bywelding cross portions between the unit 13 and the auxiliary reinforcingbars 12 and 12′, the cross arm brace 11 is manufactured. Although theexample is illustrated in which a leg portion 15 of the unit 13 is bentto an outer side, in the above-mentioned embodiment, a cross arm brace11 a is used whose unit 13 a has a leg portion 15 a which is not bent,as shown in FIG. 11. When the cross arm brace 11 has the leg portion 15which is bent to the outer side, it easy to insert the cross arm brace11 into the small space. In addition, it is possible for the cross armbrace to make friends with the light weight ball body. Furthermore, itis easy to pile the cross arm braces on storage and transportation.

Description will be made as regards another example of the cross armbrace with reference to drawings. FIG. 12 shows a prospective view forillustrating another example of the cross arm brace. The illustratedcross arm brace 16 a fixed unit 18 instead of the unit 13 of the crossarm brace 11 that is illustrated in FIG. 5. The unit 18 is composed of aholding reinforcing bar 19 which is bent to a valley shape. The unit 18is positioned to auxiliary reinforcing bars 17 and 17′ one after theother with inclination. Incidentally, the unit 18 may have a leg portionwhich is not bent, although the unit 18 has a leg portion 20 which isbent, in the above-mentioned embodiment.

The cross arm brace for the concrete slab according to the presentinvention is not limited to each of the above-mentioned embodiments andit is possible to carry out design variations in the cross arm brace.Incidentally, the light weight ball body moves on the basis of violentflow on casting the concrete when using a mesh shaped reinforcing bar,although the mesh shaped reinforcing bar such as a wire mesh, a metallath, or the like is used as the cross arm brace. It is difficult forthe mesh shaped reinforcing bar does to have a function of the cross armbrace.

In a preferred embodiment of the present invention, the small spaces 5increase in number and proposal is made about concreter slab of a smallroom type that positions smaller light weight ball bodies 5 in smallrooms, respectively. The concreter slab of small room type has a highsound insulating property in comparison to the conventional planelattice hollow concrete slab (Japanese registered Utility ModelPublication No. 3082676). In case of increasing the small rooms innumber, the interval between the main reinforcing bars of length andwidth is reduced. Under the circumstances, the sectional gap between thelower reinforcing bar 2 a and the upper reinforcing bar 3 a is reduced(with reference to Table 1). Although it is possible to further increasethe small rooms in number, it is desired to determine the number ofsmall rooms with respect to cost effectiveness, inasmuch as costincreases in the execution of construction when the number of smallrooms increases.

It is possible to form the concrete slab of the present invention bycasting the concrete in the mold form having the slab bone structure,and by casting off the concrete slab from the mold form after aging. Onforming the plane lattice concrete slab, the slab bone structure may bemade on site. Alternatively, the half PC construction method or the fullPC construction method is used according to the precast concrete plate.

Inasmuch as the light weight body positioned in the small space has aspherical shape in the plane lattice hollow concrete slab, it isunnecessary to align the light weight body in orientation on theexecution of construction. In addition, it is very easy to fix the lightweight ball body to the predetermined position by using the cross armbrace of the present invention. As a result, it is possible to exercisethe slab strength and the sound insulating property based on the design.Furthermore, it is possible to obtain a high balance between lightnessand rigidity by reducing the interval between lower reinforcing barsand/or between the upper reinforcing bars and by positioning smallerlight weight ball body in the small space. It is possible to interruptthe transmission of sound by a plurality of small spaces and the lightweight ball body positioned in each of the small spaces. As a result, itis recognized that sound having a wavelength range is attenuated. Morespecifically, it is possible to greatly improve the sonic boom of floorthat occurs in a collective housing, a hotel, a school, a warehouse, amultilevel car parking tower, or the like.

1. A plane lattice hollow concrete slab comprising a light weight bodyburied in a small space which is partitioned on a grid by an upperreinforcing bar and a lower reinforcing bar positioned on a grid in aslab, wherein: said light weight body is a solid-core or a hollow lightweight ball body; said light weight body having a diameter which passesthrough a top surface of said small space and which does not passthrough a side surface of said small space; and said light weight bodybeing fixed to a predetermined position by a cross arm brace which ispositioned on said upper reinforcing bar.
 2. A plane lattice hollowconcrete slab as claimed in claim 1, wherein a volume ratio of saidsmall space to said light weight ball body is from 10% to 50%.
 3. Across arm brace for a plane lattice hollow concrete slab, wherein: saidcross brace comprises at least two auxiliary reinforcing bars positionedin parallel between upper reinforcing bars adjacent to each other, and aplurality of units each of which is fixed downwardly on said auxiliaryreinforcing bar; each of said units being inserted into a small spaceformed by upper reinforcing bars which are positioned on a grid; and alight weight ball body being fixed to a predetermined position of saidsmall space.
 4. A cross arm brace for a plane lattice hollow concreteslab as claimed in claim 3, wherein each of said units is an endlessframe reinforcing bar which is bent to a saddle shape.
 5. A cross armbrace for a plane lattice hollow concrete slab as claimed in claim 4,wherein each of said units has a leg portion which is bent to an outerside.
 6. A cross arm brace for a plane lattice hollow concrete slab asclaimed in claim 3, wherein: each of said units comprises holdingreinforcing bars which are bent so as to form a valley, said holdingreinforcing bars being positioned one after the other with inclination;and both ends not being connected to each other in each of said holdingreinforcing bars.